1. Field of the Invention
This invention relates to squarylium dyes, and processes and intermediates for the preparation thereof. More specifically, it relates to such dyes and intermediates in which two chromophoric groups occupy the 1- and 3-positions of the squarylium ring, while the 2-position bears a substituent in which a carbon atom is bonded directly to the squarylium ring.
2. References to Related Applications
Copending patent application U.S. Ser. No. 07/616,639, filed Nov. 21, 1990, and its continuation in part, application U.S. Ser. No. 07/795,038, of even date herewith, both assigned to the same assignee as the present application describe dyes comprising an inner salt of a compound of the formula: EQU Q.sup.1 .dbd.Z--Q.sup.2
wherein:
Q.sup.1 is a 4-(benz[b]-4H-pyrylium)methylidene, 4-(benz[b]-4H-thiopyrylium)methylidene or 4-(benz[b]-4H-selenopyrylium)methylidene grouping;
Z is a 1,3-(2-hydroxy-4-oxo-2-cyclobutylidene) or 1,3-(2-hydroxy-4,5-dioxo-2-cyclopentylidene) ring; and
Q.sup.2 is a 4-(benz[b]-4H-pyran-4-ylidene)methyl, 4-(benz[b]-4H-thiopyran-4-ylidene)methyl or 4-(benz[b]-4H-selenopyran-4-ylidene)methyl grouping;
wherein at least one of the groupings Q.sup.1 and Q.sup.2 carries at its 2-position a substituent in which a non-aromatic carbon atom is bonded directly to the benzpyrylium, benzthiopyrylium or benzselenopyrylium nucleus, subject to the proviso that if this 2-substituent contains an aromatic nucleus, this aromatic nucleus is not conjugated with the benzpyrylium, benzthiopyrylium or benzselenopyrylium nucleus to which it is attached. These dyes have high absorptions in the near infra-red, and improved solubility in semi-polar solvents and plastics. The dyes disclosed in these applications include certain infra-red dyes used in the thermal imaging medium described below with reference to FIG. 4.
Copending application U.S. Ser. No. 07/696,222, filed May 6, 1991 and assigned to the same assignee as the present application, describes and claims the squarylium compounds of formulae D, E, J and K described below with reference to FIG. 1, together with similar compounds containing different heterocyclic nuclei, and squarylium compounds of the formula: ##STR2## wherein Q.sup.1 and Q.sup.2 are each independently a heterocyclic nucleus such that in the compounds of formulae Q.sup.1 CH.sub.2 R.sup.1 and Q.sup.2 CH.sub.2 R.sup.2 the methylene hydrogens are active hydrogens, the atoms of Q.sup.1 and Q.sup.2 which are bonded directly to the CR.sup.1 and CR.sup.2 groupings respectively each being part of an aromatic ring, and Q.sup.1 and Q.sup.2 are different, and R.sup.1 and R.sup.2 are each independently a hydrogen atom or an aliphatic or cycloaliphatic group. The disclosure of this copending application is discussed below in more detail with reference to FIG. 1.
Copending applications U.S. Ser. Nos. 07/695,641; 07/696,196 and 07/695,932, all filed May 6, 1991 and all assigned to the same assignee as the present application, describe and claim imaging media comprising a color-forming layer comprising a thermal color-forming composition adapted to undergo a change of color upon increase in the temperature of the color-forming layer above a color-forming temperature for a color-forming time. Preferred imaging media described in these three applications comprise three separate color-forming layers containing yellow, cyan and magenta thermal color-forming compositions; each of these color-forming compositions comprises a color-forming compound which undergoes a change of color upon heating above the color-forming temperature for the color-forming time, and an infra-red absorber (which may be referred to hereinafter as an infra-red dye) capable of absorbing infra-red radiation and thereby generating heat in the color-forming layer. The three color-forming layers use infra-red absorbers absorbing at differing wavelengths so that each color-forming layer can be imaged independently; for example, specific imaging media disclosed in these three applications use infra-red absorbers having peak absorptions at approximately 792, 822 and 869 nm.
Copending application U.S. Ser. No. 07/795,034, of even date herewith and assigned to the same assignee as the present application, describes infra-red dyes generally similar to those of the present invention, but in which the 2-substituent on the squarylium ring is an amino or substituted amino group. The dyes described in this Application include the 2-aminosquarylium dye used in the thermal imaging medium described below with reference to FIG. 4.
Copending application U.S. Ser. No. 07/795,101, of even date herewith, by Rita S. Shon Baker et al. and assigned to the same assignee as the present application, describes and claims thermal imaging media generally similar to those described in the aforementioned applications U.S. Ser. Nos. 07/695,641; 07/696,196 and 07/695,932 but in which at least one imaging layer contains a metal cation. Preferred imaging media described in this application have imaging layers containing zinc acetate, as described below with reference to FIG. 4.
The disclosures of all the aforementioned copending applications are herein incorporated by reference.